The importance of Vitamin D

As we approach the longest night of the year and the summer sunshine seems like a world away, thoughts turn to Vitamin D. Ok, well more like Christmas presents and turkey but bear with me. Vitamin D is not only essential for healthy bones through it’s management of calcium and phosphorus but also for a strong immune system, cardiovascular system and nervous system. Unlike other vitamins, the body can make it’s own vitamin D when we expose it to the sun, and subsequently turns it into a hormone (a chemical ‘messenger’ that affects the functioning of many different processes throughout the body). Unfortunately for many people who live in the Northern hemisphere, and particularly here in the UK, this is a rare occurence indeed, especially when the last winter seemed as if it would never end. Even when we do get the chance to go out in the sun, we avoid it through fear of cancer and cover ourselves in strong sunscreen laden with chemicals. So what are we to do?

As we cannot make up the shortfall by eating Vitamin D-rich foods (there is simply not enough Vitamin D in them to make a real difference), we are left with supplementation to help us out. After reading up about the importance of Vitamin D, we decided to take Vitamin D3 supplements soon after starting Paleo (April 2012). Vitamin D3 is the type produced by sunlight and is recommended over D2. These consisted of 1000iu per day and we were pretty satisfied that we were doing our best.

Some time later I read Dr Briffa’s excellent article here and began to look at the Vitamin D Council’s website too. I was interested to read the following: ‘A lack of vitamin D has also been linked to some other conditions such as cancer, asthma, type-II diabetes, high blood pressure, depression, Alzheimer’s and autoimmune diseases like multiple sclerosis, Crohn’s and type-I diabetes.’

Vitamin D deficiency appears to be especially detrimental to neurological health. According to a report on Vitamin D, nervous system and aging: ‘Clinical data suggest that vitamin D(3) insufficiency is associated with an increased risk of several CNS (central nervous system) diseases, including multiple sclerosis, Alzheimer’s and Parkinson’s disease, seasonal affective disorder and schizophrenia. In line with this, recent animal and human studies suggest that vitamin D insufficiency is associated with abnormal development and functioning of the CNS. Overall, imbalances in the calcipherol system appear to cause abnormal function, including premature aging, of the CNS.’

In light of this, I wondered if the supplementation that I was taking was enough. The Council recommends between 5000-10,000iu per day and so I decided to get a blood test done with City Assays as this seemed to be well recommended via Dr Briffa and his posters. It cost me £25. To check vitamin D status, a metabolite called 25-Hydroxyvitamin D [25(OH)D] is measured in the blood. My results came back with a reading of 50.9 nmol/L. On the results, it gave the following information:

Less than 15 – Severe deficiency

15-30 – Deficiency

30.1-50 – Insufficient

Greater than 50 – Adequate

I was basically borderline insufficient despite taking 1000iu per day for around a year. Reading up, I noticed that even above 50 was also considered rather low. According to an overview of proceedings at the Experimental Biology 2004 Symposium on Vitamin D, ‘Vitamin D sufficiency or “normal” concentrations should be defined as circulating levels of 25(OH)D > 30 ?g/L (75 nmol/L).’

In October, there were calls from Dame Sally Davies, the UK’s Chief Medical Officer to provide children with free Vitamin D supplementation due to the rising incidence of rickets. Around 40% of children may be deficient in Vitamin D and this is rising. Listening to radio interviews and news stories at the time, there was an emphasis placed on diet as a solution yet it is clear that in the absence of regular sunlight exposure, supplementation is the key. On the NHS news pages they state: ‘It is easily prevented by exposure to sunlight several times a week without wearing sun cream, as well as a balanced diet that includes plenty of vitamin D and calcium. However, in many families – often those on low incomes – the quality of children’s diets is restricted, meaning they do not receive enough vitamins and nutrients. Children who spend long periods indoors are also at risk.’ It seems to me that spending short periods outdoors in the Northern hemisphere combined with the minimal amounts of vitamin D available in food is not enough to protect from Vitamin D deficiency. If that is the case, then supplementation seems to be essential.

From an evolutionary perspective I wondered about people such as the Inuits who live in extreme Northern latitudes. How did they survive with such a low exposure to sunshine? In the interesting article ‘Vitamin D deficiency among northern Native Peoples: a real or apparent problem?’ it states that although levels of vitamin D are low, this does not necessarily indicate a deficiency for these northern Native peoples. Pre-European skeletons show no signs of rickets and it seems that the people have naturally adapted to low levels of the vitamin over time. However, the article goes on to state that the incidence of rickets in such populations is rising. This seems paradoxical considering the fact that we would expect evolutionary adaptation to the shortage, so what is happening? The article goes on to state that ‘…dietary causes are ubiquitous. Northern Natives eat much less meat now than in the past, and a high meat diet seems to reduce the risk of rickets independently of vitamin D intake…Modern diets also contain substances that react with calcium or phosphorus to form insoluble salts, thereby depleting the body’s supply of usable calcium and phosphorus. Such substances include phytic acids in commercially processed cereals, sodium bicarbonate in baking soda, and aluminum hydroxide in antacids.’ It is interesting that a move away from their traditional diet could possibly be contributing to the incidence of rickets. I wonder if this applies to other populations? Could rising levels of rickets in children be due not only to a lack of sunshine, but also to a diet predominantly focused on cereals at the expense of meat and fish? This is something that wasn’t discussed in the news articles about rickets. The focus was clearly on eating oily fish and vegetables (no mention of meat), but no word on whether eating a high-cereal diet could be a contributing factor.

When I received my results, I was pretty surprised to say the least and immediately looked for some higher strength supplements as a precaution. We now take 5000iu a day and sometimes up to 10,000iu. I think we pay around £10 for a bottle of 360 tablets containing 5,000iu per tablet, so it’s pretty good value compared to the cost of Vitamin D deficiency.